Hammer mills



United States Patent HAMMER MILLS Thomas C. Whisler, Sr., Alameda, Calif., assignor to American Brake Shoe Company, New York, N.Y., and Wilmington, Del., a corporation of Delaware Filed Dec. 2, 1957, Ser. No. 700,048

12 Claims. (Cl. 241-195) This invention relates to a hammer for a hammer mill, the hammer having a reversible tip.

One type of hammer mill is one in which the direction of rotation of the shaft, discs, and hammer assembly operating therein can be changed by merely changing the direction of the driving means for the shaft. It has been proposed to reverse the direction of rotation of the hammers when the working faces that constitute the leading ends of the hammer tips are excessively worn, whereby the opposite or unworn tip ends areutilized.

In another type of mill, the hammers are provided with removable, reversible tips which, when worn excessively at the leading ends, are removed and then reversed on the hammer shanks. The reversing operation can involve considerable time, especially in those instances where the shank of the hammer must also be dismounted in order to effect reversal of the tip. Theprimary object of the present invention is to enable reversing of the tip to be accomplished in a novel manner without removal of the shank from the rotating shaft of the mill on which the hammer shank is carried. Thus, in most mill the two end rows of hammers are so close to the end plates of the mill that it is a laborious and time-consuming task to drive out a Wedge key by means of a hammer or to disassemble cotters, pins or like retainers used to hold the removable tip to the shank. Under the present invention, and this constitutes a specific object, the tip and the shank members have interfitted parts with aligned openings therein. At least one such opening has a fiat inclined surface constitutinga wedge surface, and a bushing is complementally fitted in suchopenings and has a wedge surface thereon complemental to the aforesaid wedge surface. The bushing is internally threaded and a screw, inserted through and reacting on one of the interfitted' parts, is turned in the bushing, the bushing serving as a nut which in effect .runs up on the screw bringing the wedge surfaces into tight engagement thereby dismountably locking the tip to the shank. Y

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in theaccompanying drawing which, by way of illustration, shows a preferred embodiment of the present invention and the principle thereof and what is now considered to be the best mode contemplated for applying that principle. .Other embodiments of the invention embodying the same or equivalent principle may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

In the drawings: 7 Fig. 1 is a side elevation of a hammer constructed in accordance with the present invention;

Fig. 2 is a side elevation of theshank of the hammer on a reduced scale;

Fig. 3 is a side elevation of the tip of the hammer on a reduced scale;

Fig.4 is a view part in elevation and part in section taken on the line 44 of Fig. 1; and

2,962,232 Patented Nov. 29,

Fig. 5 is a view of the assembled bushings.

The present invention is illustrated in Fig. 1 of the drawing as embodied in a hammer 10 having a shank 11 and a removable and reversible tip 12 mounted on the lower end thereof. The tip 12 is attached to the lower end of the shank in a manner to be explained, and the shank adjacent the opposite end is formed with a relatively large opening 13 enabling the hammer to be mounted on the operating shaft in the mill.

As shown in Fig. 2, the shank '11 has an arcuatetop surface 15 and front and rear surfaces 16 and 17 which diverge relative one to the other in a downward direction. It should be mentioned that all parts of the hammer in the form illustrated are fully symmetrical, and hence reference to front and rear portions is merely for purposes of definition. The lower ends of the front and rear surfaces or Walls 16 and 17 of the shank are directed inwardly at 18 to provide downwardly facing shoulders, and the bottom of the shank 11 is in the form of a rela tively large arcuate lug having a rounded bottom face or wall 21 representing the lowermost'area of the hammer shank. It will be appreciated that for the most part the hammer 10, particularly the shank and the tip, comprises cas-t parts, and preferably the tip 12 will .be cast of -a wear-resistant alloy having a long wear life and high impact strength such as manganese steel or the like.

The shank and tip members have complemental inter.- fitting parts establishing a union between the tip and the shank. The preferred manner of establishing such interfitting parts is shown in Fig. 4 and fundamentally consists in forming a mounting recess in the shank extended upwardly from the bottom face of the shank 11,- and in providing the tip 12 with a projection .complemental thereto. Thus, as shown in Fig. 4, a relatively large mounting recess 25 opens at and is extended upwardly from the bottom face 21 of the hammer shank, this recess being accurately centered medially of the bottom face of the hammer shank.

The tip 12 of the hammer, Fig. 3, includes a head 26 having sloped front and rear walls 27 and ,28 whichconverge upwardly proceeding from the bottom faceor wall 30 of the tip 12 so as to be substantially co-planar with the corresponding walls 16 and 17 of the hammer shank. The surfaces 27 and 28 of the tip are symmetrical and constitute alternate impact faces or ends. In other words, if during use ofthe hammer the end 27 or ,28, whichever ice happens to be the leading end, becomes unduly Worn, it

is merely necessary to dismount the tip and reverse the .same relative to the shank in a manner apparent from .the

description to follow. a a

.As shown in Fig. 3, a projection 35 projects upwardly on the side of the tip 12 opposite the bottom face thereof and is of course cast integral with the tip 12. Themejection .35 is of reduced width in comparison to the head 26 of the tip, and the head 26 includes arcuate upwardly facing shoulders as 37, Fig. 3, engageable with the bottom face of the shank 11 when the tip is mounted thereon. As will be observed in Figs. 1 and 2, the internal Wall 25W in the shank 11 which defines the upper limit of the recess 25 is complemental to the arcuate back 35B of the projection 35 on the tip. Additionally, the mergance of the ends of the projection 35 with areasadjacent the front and rear walls of the tip is flattened at 30 and 31, Fig. 3, so as to be complemental to the inwardly directed shoulders as 18 of the shank 11.. It should be further mentioned that the retainer means to be described hereinafter and the openings in which the retainer means are mounted are so oriented as to establish some spacing as at 8-1 and 8-2, Fig. 1, between the opposed surfaces of the projection on the tip and the shank to facilitate interfitting of the parts and to enable some take-up or play to ,be afforded.

The internal recessing of the shank establishes what can be termed a pair of side plates 40 and 41, Fig. 4, on the shank, and relatively large openings 43 of identical size, configuration and orientation are extended therethrough, whereby the outer ends of the openings 43 open at the outer faces of the plates 40 and 41 and the inner ends of the openings 43 communicate with the internal mounting recess 25. Likewise, a relatively large opening 46 is formed in the projection 35 on the tip 12, and when the tip 12 is mounted to the shank 11 with the projection 35 thereof disposed in the mounting recess 25, the opposite ends of the opening 46 in the tip registers with the inner ends of the openings 43 in the side plates of the hammer shank.

The outer ends of the opening 46 in the tip member are formed with sloped fiat faces 50 located at the upper extremity of the opening 46. Each such fiat face 59 constitutes a wedge surface, and as shown particularly in Fig. 4 the wedge surfaces 50 converge toward the 'medialdiameter of the opening 46 so as to have-a common base line. When the tip is properlyinterfitted in the mounting recess of the shank, the wedge surfaces 50 are aligned with a pair of key slots 43K located at the top of the openings 43 in the side plates of the hammer shank. Additionally, the tip 12 is formed with a narrow crescent shaped rib R. The rib R is joined integra ly to the head 26 of the hammer tip and is of reduced width in comparison thereto as will be seen in Fig. 4. The rib R is joined at the opposite ends to the projection 35, and

when the tip is mounted on the shank the rib R is dis- :posed in the recess 25. Should one end or the other of the tip be worn through during use, the head of the hammer tip will remain integrated by the rib R.

Under the present invention, the tip is retained on the shank by cooperating wedge surfaces, and screw means are utilized to draw the wedge surfaces into engagement. The retainer means is conveniently in the form of a pair of bushings 51 and 52, Figs. 4 and which exteriorally are complemental to the openings 43 in the hammer shank including the key slots 43K. In exterior appearance, the two bushings are substantially identical, with the exception that the bushing 52 is formed with a rela- "tively largerecess 53 in the exterior end thereof Whereas the bushing 51 is formed with a somewhat smal er recess 54 in the exterior end thereof. Thus, each bushing has 'a round body portion 55, Fig. 5, of uniform diameter,

and the inner end portion of each bushing is of rounded tapered form at 56 to facilitate entry into the openings 43 of the hammer shank. Each bushing at what constitutes the top thereof is formed with an integral projecting abutment or key 58, Fig. 1. which fits in the related key slot 43K thereby locating the bushing in the related opening of the shank against rotation. The key proiection 58 thus has a fiat upper surface, as shown in Figs. 1 and 4, spaced slightly below the opposed flat horizontal surface of the key slot 43K, and the vertical shoulders 61 and 62 of each key 58 are spaced somewhat inwardly of and directly opposite the corresponding vertical shoulders 63 and 64 of the related key slot 43K. Hence, rotation ofeither bushing 51 or 52 is limited to the extent that a pair of such shoulders eventually engage with one another.

Each key as 58 is in effect extended from the outer to the inner end of the bushing, and the inner end portion of each key 58 is tapered radially inwardly of the bush ing to afford a wedge surface 65' complemental with the related wedge surface 50 afforded by the configuration of opening 46 in the projection 35 of the hammer tip as described above. Hence, upon positioning a bushing so that the outer portion thereof reposes in an opening 43 in the shank and the inner portion thereof is disposed in the-opening 46 in the tip with the related wedge surfaces 50 and 65 engaged, the tip 12 is held to the shank against displacement. By drawing such wedge surfaces into tight engagement, the tip 12 is tightly locked to the shank 4 whereby the tip and shank members are rigidly united for the desired impacting operation within the hammer mill.

In achieving the desired tight engagement between the wedge surfaces 50 and 65', the bushing 51 is threaded internally at T to serve .as, a nut. The threaded opening T communicates with the recess 54 in the outer end of the bushing 51. The other of thebushings 52 is formed with an axial-through bore 65 which communicates with the recess 53 and which, when the bushings are in place, is accurately aligned with the threaded opening T in the bushing 51 through the unoccupied medial portion of the opening 46 in the tip. A cap screw having a threaded shank 66 and a hex head 67 is positioned so that the threaded shank 66 thereof is passed freely through the bore 65 and the opening 46 in the tip with the threaded end of the shank threadedly connected to the threaded bushing 51. The head 67 of the screw is adapted to repose in the recess 53 in the outer end of the bush ing 52, and a lock washer 68 is preferably disposed between the bushing 52 and the head 67. Hence, by rotating the screw in the proper direction, the bushing 51 in effect runs up on the screw and at the same time the two bushings are drawn inwardly toward one another until the two wedge surfaces 65' of the bushings tightly engage the two wedge surfaces 50 to the desired extent.

The foregoing rigid attachment of the tip of the shank can of course be conveniently accomplished by a suitable socket wrench. In dismantling the tip incidental to reversal of the tip relative to the shank, it is merely necessary to back the screw off to the extent that it is disconnected from the threaded bushing 51. The screw is then pulled outwardlytogether with the bushings 51 and 52 to free the projection 35 of the tip, whereby the tip can be removed, reversed and the parts re-assembled. It will be realized that the entailed operations require no force driving of wedges or pins or pinching of cotters or the like which ordinarily require rather extensive working space to enable the entailed manual manipulation to be carried out.

It will be seen from the foregoing that under the present invention a reversible tip for a hammer mill hammer is conveniently and effectively joined operatively to the hammer shank by means including a retainer bushing mounted in an opening in one of the hammer members and having a wedge surface thereon for engaging a wedge surface on one of the hammer members. The retainer is tightly drawn up in position to produce tight engagement of the wedge surfaces by means of a screw reacting against one of the hammer members. In the specific form of the invention disclosed, such reaction is established through the medium of a second bushing also having a wedge surface engageable with a wedge surface on one of the hammer members, and such assures the establishment of uniform retaining forces and also makes possible a substantially simplified and fully symmetrical construction. Assembly and disassembly is advantageously effected merely by turning the screw.

Hence, while I have illustrated and described a preferred embodiment of my invention it is to be understood that this is capable of variation and modification, and I therefore do not wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall within the purview of the following claims.

I claim:

1. A hammer of the kind described comprising, an elongated shank and a removable tip at one end of the shank, said tip and shank having complementally interfitting parts establishing a union between the tip and the shank, said parts having openings therein and the opening in one of said parts being but partly defined by a flat substantially planarwedge surface, a retainer having a portion disposedin said opening having the wedge surface and holding the tip to the shank, said re- -tainet' having a wedge surface thereon complemental to and engaging the first-named wedge surface, and means inserted in the opening in the other of said parts and coupled to said retainer for tightly drawing said wedge surfaces into engagement to lock the tip to the shank.

2. A hammer of the kind described comprising, a shank and a removable tip for the shank, said tip and shank having complemental interfitting parts establishing a union between the tip and the shank, said parts having registered openings therein and the opening in 'one of said parts being but partially defined by a flat substantially planar wedge surface, a retainer having por- 'tions respectively disposed in said openings and holding the tip to the shank, said retainer having a wedge surface thereon complemental to and engaging the firstnamed wedge surface, and screw means inserted in the opening in the other of said parts for tightly drawing said wedge surfaces into engagement to lock the tip to the shank.

3. A hammer of the kind described comprising, a shank and a removable tip for the shank, said tip and shank having complementally interfitted parts establishing a union between the tip and the shank, said interfitted parts having registered openings therein and the opening in one of said interfitted parts being but partially defined by a flat substantially planar wedge surface, a nut-type retainer having end portions respectively disposed in said openings and holding the tip to the shank, said retainer having a wedge surface thereon complemental to and engaging the first-named wedge surface, and a screw inserted in the opening in the other of said parts and threadedly coupled to said retainer for tightly drawing said wedge surfaces into engagement to lock the tip to the shank.

4. A hammer of the kind described comprising, a shank and a removable tip for the shank, said tip having a projection thereon and said shank having an internal mounting recess in which said projection is disposed to establish a union between the tip and the shank, said projection on the tip having an opening therein formed with a wedge surface which occupies but a part of said opening and which is flat and substantially planar, said shank having an opening therein registered with the opening in said projection, a nut-type bushing mounted in said registered openings and having a wedge surface thereon engaging the first-named wedge surface, and a screw threaded in said bushing for tightening said bushmg.

5. A hammer of the kind described comprising a shank member and a removable tip member for the shank member, said members having complementally interfitting parts establishing a union between said members, one of said members being formed with an opening but being partially defined by a flat substantially planar wedge surface, a separable retainer member disposed in said opening and having a wedge surface thereon complemental to and engageable with the first-named wedge surface, and means positioned in the other of said members and coupled to said retainer member for drawing said wedge surfaces into engagement and maintaining such engagement.

6. A hammer of the kind described comprising a shank member and a removable tip member for the shank member, one of said members having a mounting recess therein and the other of said members having a projection fittable complementally in said recess for establish- 7 ing a union between said members, the member having said projection being formed with an opening but being partially defined by a flat substantially planar wedge surface, a separable retainer member disposed in said opening and having a wedge surface thereon complemental to and engageable with the first-named wedge surface, and means positioned in the other of said members and coupled to said retainer member for drawing said wedge surfaces into engagement and maintaining such engagement. T 7. A hammer of the kind described comprising a shank member formed with a shaft-receiving opening at one end and a removable tip member for the opposite end of the shank member, one of said members having an internal mounting recess therein and the other of said members having a projection fittable complementally in said recess for establishing an internal union between said members, said members being formed with' registered openings and one of said openings being but partially defined by a flat substantially planar wedge surface, 'a separable nut member disposed in one of said' openings and having a wedge surface thereon complemental to and engageable with the first-named wedge surface, and a screw positioned in the other of said openings and threaded in said nut member for drawing said wedge surfaces into engagement and maintaining such engagement.

8. A hammer of the kind described comprising, a shank and a reversible tip for the shank, said shank having a fully symmetrical bottom face and an upwardly extended mounting recess located medially of said bottom face and defining a pair of identical side plates for the shank, openings in said side plates, said tip being fully symmetrical and having alternate impacting ends and a bottom face, a projection located medially on said tip opposite said bottom face and formed substantially complemental to said mounting recess, said projection having an opening formed therethrough, at least the outer ends of said opening in the tip projection being formed with flat wedge surfaces, the outer ends of said opening in the tip being in registry with the inner ends of the openings in the shank when the tip is mounted on the shank with the projection thereof fitted complementally in the mounting recess in the shank, a pair of bushings mounted in the openings in the side plates of said shank with the inner end portions thereof reposed in the opening in said tip at the outer ends thereof, said bushings having fiat wedge surfaces complemental to the first-named wedge surfaces and in engagement therewith, and screw means for drawing said bushings inwardly toward one another to produce a tight wedge fit between said wedge surfaces.

9. A hammer according to claim 8 wherein, one of said bushings has a recess in the outer face thereof, a screw is extended through said one bushing and through the opening in said tip, said screw having a cap reposed in the recess of said one bushing, and wherein the other of said bushings is threaded as a nut and run up on the end of said screw opposite said head.

'10. A hammer of the kind described comprising, a shank and a removable tip for the shank, said shank having a bottom face and a mounting recess extended upwardly from and opening at said bottom face, an opening in said shank in communication with said mounting recess, said tip having a bottom face and a projection on said tip opposite said bottom face and formed substantially complemental to said mounting recess, said projection having an opening formed therethrough, at least one of the outer ends of said opening in the tip being formed with a flat wedge surface, said opening in the tip being in registry with the inner end of the opening in the shank when the tip is mounted on the shank with the projection thereof fitted complementally in the mounting recess in the shank, a nut-type bushing mounted non-rotatably in the opening in said shank with the inner end portion thereof reposed in the opening in said tip, said bushing having a flat wedge surface complemental to the first-named wedge surface and in engagement therewith, i

and screw means passed through said shank and the opening in said tip and threadedly connected to said bushing for drawing said bushing inwardly to produce a tight wedge fit between said wedge surfaces.

11. A tip for a hammer of the kind described comprising, a'headhavinga bottom face and an impacting end surface, a projection on said head opposite the bottom face, said head and projection being fully symmetrical throughout, said projection having an opening therethrough and said opening being defined in part by a pair to receive the head of a cap screw, and an integral key projecting radially from said body member for holding the bushing against rotation within said hammer shank,

said body portion having a fiat planar surfaceadjacent one .end which surfaceslopes radially inwardly from an upper surface of. said key toward said one end for engaging a complementalsurface on a hammer tip to adjust the radial disposition of the hammer tip with respectto said bushing.

References Cited in the file of this patent UNITED STATES PATENTS 36,302 Murray Aug. 26, 1862 526,308 Garvin Sept, 18, 1894 1,724,786 Von Buskirk Aug. 13, 1929 1,940,116 Brooks Dec. 19, 1933 2,388,272 Lord Nov. 6, 1945 2,605,972 Le Blane Aug. 5, 1952 2,663,505 Sennholtz Dec. 22, 1953 2,712,417 Jensen July' 5, 1955 

